1. Field of the Invention
The present invention relates to a method for preparation of composite pigments for make-up cosmetics. More particularly, it relates to a method for preparation of composite pigments for make-up cosmetics having improved skin-adhesion and spreadability, and excellent skin color-expression, and improved water resistance by silicon polymer coated on the surface of the composite particle of flaky silica and titanium dioxide coated thereon. Also, it relates to a make-up cosmetic composition containing the above composite pigments.
2. Description of the Prior Art
In general, synthetic silica for make-up cosmetics has spherical, flaky or acicular particles and among them, porous or hollow silica having spherical particles with average particle diameter of 3.about.15 .mu.m has been widely used. The spherical silica can increase fluidity of the content in make-up cosmetic composition due to its conformational property. But, the increased fluidity may maldistribute make-up film to a direction of force to be applied onto the skin, resulting in forming uneven film. And, spherical particles tend to roll on the skin, rather than to slide, resulting in poor spreadability. Further, minimum contact area of the spherical particles may cause poor skin-adhesion.
Accordingly, in order to overcome the foregoing defects of the spherical silica, a method for producing a flaky silica has been proposed in U.S. Pat. No. 4,882,133. The method comprises steps of coating silica hydrosol onto a surface of the roller and then heating to form silica hydrogel; vaporizating dispersion medium to shrink and scrap off the silica hydrogel, to give amorphous silica; and heating at a high temperature to give flaky silica with uniform thickness. The obtained flaky silica has improvement in spreadability and skin-adhesion, but has excessive light-transmittance, resulting in poor skin-color expression. So, this flaky silica is improper as an ingredient of make up cosmetics.
Meanwhile, in order to obtain extender pigments having improved skin-adhesion and spreadability, a coating technique has been developed rapidly. For example, there have been provided composite pigments prepared by coating talc, mica, sericite and the like with ultrafine titanium dioxide. The pigments such as talc, mica and sericite have good spreadability, while the ultrafine titanium dioxide has good skin-adhesion. Such composite pigments have been successful in obtaining good result in both skin-adhesion and spreadability, and so have been widely used in base make-up cosmetic products such as twin-cake, powder foundation, liquid foundation and makeup base. However, the pigment derived from clay mineral, for example, talc, mica or sericite has high gravity of 2.5.about.2.8, and the composite pigments prepared therefrom have also high gravity, to show heavy feeling onto the skin.
Under this circumstance, the present inventors have conducted extensive studies in order to solve the above problem or drawback and to provide new composite pigments having improved skin-adhesion and spreadability, and having appropriate transmittance to the skin color. As a result, they found that composite pigments prepared by coating flaky silica with ultrafine titanium dioxide can achieve the above objects, and in addition show light feeling onto the skin.
Based on this finding, the present invention can be accomplished.